The present invention relates generally to sewerage systems which utilize differential pressures to produce sewage transport through the system as contrasted with the more conventional gravity-operated and positive pressure sewerage systems. More particularly, the invention relates to a sub-surface in-pit breather system for a vacuum sewerage transport system and to the prevention of fluid accumulation in a valve control apparatus.
A typical vacuum sewerage system generally comprises a vacuum collection station which is connected to one or more vacuum sewers, often several miles in length. These sewers extend radially outwardly from the station and are equipped at frequent intervals with vacuum sewerage interface valves. These valves act as an interface, for example, between the vacuum sewer and one or more gravity lateral lines which may, for example, extend from a sewage source such as a residential home.
The general structure and method of operation of the vacuum valve and a sewer network utilizing such valve are described in U.S. Pat. No. 3,777,778 (Janu); U.S. Pat. No. 4,373,838 (Foreman and Grooms); and U.S. Pat. No. 4,179,371 (Foreman and Jones). Attention is also directed to U.S. Pat. No. 4,171,853 (Cleaver, et al) which describes in detail other components of a typical vacuum sewerage system.
These known vacuum sewerage systems have required direct connection of an above ground breather pipe to the vacuum interface system to prevent flooding of the controller-sensor unit by water filling the pit in which the valve is housed. All known systems prior to this invention have prevented controller-sensor flooding and failure from ground water accumulation by use of an above ground and water level air breather pipe.
However, the above round and water level air breather pipe has many disadvantages, not the least of which is the problem of aesthetics with respect to the widely varying above ground environs in which these pipes protrude. Other drawbacks include susceptibility to vandalism as well as unintended or accidental damage which may cause the vacuum interface valve to malfunction.